One of the best parts about owning an electric outboard is that you don't need to winterize it like a gas motor! But there are a few things you should do in the Fall and over the Winter to ensure that your electric outboard (and its battery) will work properly in the Spring and for years to come.
Preparing your Electric Outboard for the Winter
Rinse your motor thoroughly with fresh water to remove any salt and prevent corrosion. For motors like the ePropulsion Spirit 1.0 Plus and Torqeedo Travel, it's important to turn your motor about 90 degree off center and spray water down the shaft, which is hollow.
Inspect the anodes on your electric outboard. If about 25% or more of the original anode has corroded away, it's time to swap it out for a new one. We recommend doing this in the Fall instead of the Spring because it's usually easier to remove the old anodes sooner rather than later.
If you want to get ahead of the curve, you can take care of some of the items on our Electric Outboard Spring Time Checks. Some of these items do need to be done in the Spring, but others, like checking your electric outboard's anodes, can be done in the Fall.
Preparing your Electric Outboard Battery for the Winter
Before we get into preparing your electric outboard battery for the winter, it's important to understand a few concepts around battery health, chemistry, and storage.
State of Charge & Battery Health
Lithium batteries like being around 50% state of charge. Think about it like this: when your lithium battery is below 20% SOC or over 80% SOC, it's stressful for the battery, which adversely impacts its long term health. Between 20% and 80%, your battery is relaxed. So, ideally, your electric outboard battery spends most of its life in that range, and is only below 20% or above 80% for short periods of time. The more time your battery spends relaxed, the longer it will will last.
Self-Discharge & Ghost Drain
Lithium batteries slowly lose their charge, even when youn aren't using your electric outboard. There are two causes for this: true self-discharge and "ghost drain" or parasitic load.
Self-discharge is the natural internal loss inside a lithium battery and happens even when the battery is disconnected from your electric outboard. It's caused by tiny internal chemical reactions and can't be stopped, only minimized. Most lithium batteries have a self-discharge rate of 1-3% per month.
Ghost drain or parasitic load refers to the energy used by electronics that pull power from the battery, even when you're not running your electric outboard. This could be things like the battery's BMS (battery management system) or its Bluetooth connectivity. For most portable electric outboards, ghost drain isn't a major issue because there aren't many things pulling power from the battery when it's not in use.
Deep Discharge
This is the thing you really, really want to avoid. Your electric outboard battery is made up of a number of individual lithium battery cells that come together to produce the rated voltage of the battery. The voltage of these cells, and the voltage of your battery as a whole, fluctuates based on your state of charge.
For example, the ePropulsion Spirit Battery Plus has a rated voltage of 48V, a maximum voltage of 52.2V and a cutoff voltage of 33.6V. When you're near 100% SOC, you're around 52.2V, and when you're near 0% SOC, you're around 33.6V.
If you run your battery down to 0% SOC, it isn't truly "dead." There's still energy in those cells, they've just reached their cutoff voltage. If you don't charge your battery right away, it will continue to self-discharge, bringing the voltage below the cutoff voltage.
Once this happens, the battery cannot be charged with a regular charger; the cells would need to be recovered by charging them on a cell by cell level. This is time consuming and expensive. For large batteries, it might be cost effective to do this. But for most portable electric outboard batteries, this isn't the case. If your battery becomes deeply discharged, it will likely need to be recycled, and you'll need to purchase a new battery.
What this Means in Practice
Exact winter storage parameters vary by manufacturer, but the general idea is the same: charge it to somewhere between 50-80%, then check the state of charge (SOC) every three months. If it has dropped below 50-80%, charge it, then wait another 3 months.
Doing so keeps your battery in a relaxed state and avoids letting your battery become deeply discharged. Adhering to these guidelines will help you avoid the significant cost of replacing your battery sooner rather than later!
It's also important to touch on temperature. Long term exposure to high or freezing temperatures adversely impacts the longevity of your battery. Over the winter, store your battery somewhere inside where it won't get too hot and won't routinely be exposed to freezing temperatures. Make sure this place is relatively dry and doesn't have particularly high humidity. Again, exact recommendations vary by battery and manufacturer. Scroll down to see these recommendations for our most popular motors.
Electric Outboard Winter Storage FAQ
I charged my battery to 100% before winter storage. What should I do?
Ideally, you'd run the battery down to the recommended winter storage SOC. The only way to do this is by running the motor on your boat or in a water tank. If this isn't practical, it's not the end of the world. Your battery will slowly self-discharge and reach the recommended SOC over time.
I'm afraid that my batter is deeply discharged. What should I do?
Plug your battery into the charger and leave it charging for a day or so. Attempt to check the SOC again. If your motor won't turn on, your battery is likely deeply discharged. If you happen to have a local service center nearby or a friend with the same motor/battery, you can try the motor with another battery (or vice-versa) to confirm that the issue is with your battery and not your motor.
You can also reach out to us directly for help. If you own a Torqeedo electric outboard, you can also reach out to your closest Torqeedo Service Center.
How long is long term storage?
Most manufacturers don't clearly define long term storage. To be conservative, we'd say that you should prepare your electric outboard battery for long term storage if you don't plan to use it for more than a few weeks. Again, the most important thing is to avoid a deeply discharged battery; if you run your battery down below 20% SOC, charge it back to at least 50% SOC as soon as possible.
Winter Storage Recommendations by Manufacturer and Motor / Battery
If your SOC has dropped below the manufacturer recommended level when you check it during winter storage, charge the battery back to the recommended level before returning it to winter storage.
ePropulsion Spirit Battery Plus
Ideal storage temperature: 59ºF - 77ºF
Check SOC every: 3 months
Ideal SOC for long term storage: 60% (make sure to charge just over 60%)
How to check SOC: Plug into Spirit 1.0 Plus / Evo motor or ePropulsion Spirit Battery Activator
Other important information: The ePropulsion Spirit Battery Plus has a deep sleep mode that minimizes the rate of self discharge. If your SOC is above 60% and the battery hasn't been used for a while, it will go into deep sleep mode, where self discharge drops to a very slow rate. Once the battery is in deep sleep mode, the only way to wake it up is by plugging it in to a charger.
ePropulsion Spirit Battery Ultra
Ideal storage temperature: 59ºF - 77ºF
Check SOC every: three months
Ideal SOC for long term storage: 45% - 50%
How to check SOC: Button on battery or plug into motor. See chart below on how LED indicator reflects SOC. We recommend plugging the battery into the motor so you can see your exact SOC.
ePropulsion eLite
Ideal storage temperature: 59ºF - 77ºF
Check SOC every: three months
Ideal SOC for long term storage: 45% - 50%
Definition of long term storage: more than a few weeks
How to check SOC: Click the button on the top of the eLite
Torqeedo Travel Battery / Battery XP
Ideal storage temperature: 41ºF - 59ºF
Check SOC every: three months
Ideal SOC for long term storage: 50%
How to check SOC: Plug the battery into the motor
Remigo One / Neo
Ideal storage temperature: 59ºF - 77ºF
Check SOC every: three months
Ideal SOC for long term storage: 50% - 80%
How to check SOC: Put kill switch / key on the motor and observe LEDs